I would like to get some recommendations for an open source Learning Content Management System.

My requirements are simple.

0. It must run on Unix.
1. The application must be based only on HTML and PHP (NO Java please)
2. The application must be accessible with the browsers supporting only OpenSSL (NO Javascript nonsense or God forbid Java\Flash plug-ins)
3. It must support grade book.
4. It must support uploading of files.

In particular, I would like to hear from people having experience with ATutor and Moodle.